Solid compositions useful as disinfectants and cleansers are well known in a number of contexts, i.e., as detergents, bleaches, and the like. Toilet cleaner and disinfectant compositions in the form of solid tablets and "cleansing blocks" have also been described, for example, in U.S. Pat. No. 4,683,072 to Holdt et al. and U.S. Pat. No. 4,460,490 to Barford et al., respectively. As explained in Holdt et al., cleaning and disinfectant tablets used to sanitize toilet bowls contain numerous components such as bleaches, germicides and other disinfectants, salts, acids, complexes, disintegration rate regulators, plasticizers, and the like. Barford et al., similarly, describes cleansing compositions for toilets, the compositions containing a number of different types of ingredients, including bleaching agents, dyes, fillers, water softeners, anionic surfactants, and the like. Solid disinfectant and cleansing compositions are also described in U.S. Pat. No. 4,741,853 to Walker et al. and U.S. Pat. No. 5,110,868 to Bellis et al., both of which focus on the controlled release of the chemicals contained in the sanitizing blocks.
As the components of these compositions can be quite corrosive, it has proven difficult to prepare a stable, long-lasting formulations. This is especially true with compositions containing halogen-releasing agents, particularly hypohalite-releasing agents such as the hypochlorite- and hypobromite-releasing bleaches. Halogen-releasing agent are frequently viewed as preferable to other types of halogenating or oxidizing agents, particularly in sanitizing applications or in other contexts where powerful cleansing agents are required. However, the fact that halogen-releasing agents are such strong oxidizing agents can cause problems with stability and shelf-life.
Furthermore, the reactivity of halogen-releasing agents has made it difficult to incorporate chemically sensitive components which would otherwise be desirable, e.g., aesthetic additives such as fragrance and colorant. European Patent Publication No. 206,725 ("Lavatory Cleansing Compositions"), inventors Barford et al., notes the importance of excluding any components from a solid bleach composition which would be susceptible to degradation by the extremely reactive halogen-releasing agents used, e.g., halogenated dialkylhydantoins. For this reason, several products are currently marketed as "two-tablet" systems, with one tablet containing bleach and the second tablet containing a colorant.
In addition, halogenated derivatives of dialkylhydantoins such as dimethylhydantoin are very fine, dusty powders which are difficult to compact into solid, high integrity forms such as compressed tablets or blocks. Thus, the manufacture of hydantoin blocks and tablets has proved problematic. There is not, at present, a completely acceptable way of manufacturing solid disinfectant and cleansing compositions containing a halogen-releasing agent such as a hydantoin, i.e., a method which involves simple and straightforward technology and provides a chemically and physically stable product. The currently used processes for manufacturing solid disinfectant and cleansing compositions involve the need for compaction, granulation, or the like, and the associated manufacturing and control systems. UK Patent Publication No. 2,276,345A ("Process for Making Shaped Articles"), inventor Adams, describes such a process, which involves compacting and molding detergent compositions into finished "shaped articles." European Patent Publication No. 206,725, cited above, describes an extrusion process for making solid hydantoin tablets which requires significant quantities of anionic surfactant (the exemplified formulations contain 32 wt. % to 58 wt. % anionic surfactant). The compositions do not incorporate any potentially bleach-sensitive perfumes, dyes, or the like.
Accordingly, there remains a need in the art for a solid disinfectant and cleansing composition which is stable and long-lasting, can contain chemically sensitive components such as fragrance and colorant in addition to a halogen-releasing agent, and is readily manufactured using a simple extrusion process. Extrusion provides for a number of advantages relative to conventional tabletting processes. One such advantage is an increase in the uniformity of the composition; tabletting, in contrast to extrusion, can result in particle segregation. An additional advantage, as alluded to above, is the use of a lower pressure process, which enables incorporation of pressure-sensitive materials such as encapsulates and the like. Still an additional advantage is the capability of adding liquid materials to the composition during the extrusion process, something that is not feasible with conventional tabletting methods.